Generally they are in the X.lua file in wtf/account/youraccountname/savedvaribles and then another in ...../youraccountname/yourservernam/yourcharactername. Or just search the wtf folder for "bartender" with wild cards before and after.

Generally speaking, at least with Ace files for sure, you need to go into those .lua files and change each occurence of the "oldcharactername" to the "newcharactername", before replaceing the files in the newcharacter folder with the old one.

Have fun.